In the oil and gas industry, it is increasingly common to inject water and/or steam into reservoirs (such as, e.g., an oil reservoir). These types of injections may be utilized to maintain or control a pressure within a reservoir and/or to introduce heat into the reservoir (e.g., to change a temperature within the reservoir). Water injected into a reservoir may replace extracted mass (e.g., oil) and, thus, influence a pressure in the reservoir. Steam injected into the reservoir may both replace extracted mass and cause changes in temperature.
Operators of wells often use programmable logic controllers (PLCs) to control the injection of water and/or steam into a reservoir. However, PLCs require Alternating Current (AC) power to operate, which requirement is unique as compared to the power requirements of other components at the site of a well. That is, other than a PLC, typical components of a process control system at the site of a well do not require AC power, and, in order to utilize PLCs to control the injection of water and/or steam (e.g., at a wellhead), operators must spend large sums of money to ensure that AC power is available at the sites of wells.
Moreover, some major oil operators are at least considering a classification of AC power sources (e.g., 120V AC) as “hazardous.” If these operators make such a classification, only properly suited and licensed electricians will be able to service PLCs at the sites of wells, and this requirement would result in further costs associated with the use of PLCs to control water/steam injection. A use of PLCs can further result in a lack of consistency between injection processes. Because each PLC is individually programmable, one PLC controlling injection at a first wellhead may operate differently than another PLC controlling injection at a second wellhead. In such a case, operators are forced to send PLC programmers to make changes to the PLCs at each of the sites.